The invention is directed to a sound reproduction system composed of a multiplicity of loudspeakers with tapered slot couplers driven by a sound energy generating arrangement. The sound receiving domain may include a concert hall, auditorium, an open air arena, living rooms, dens or the like, wherein loud-speakers of different capabilities combine to generate a listening ambience being very close to that of a real performing ensemble of musical performers and instruments.
One of the major elements of the invention is a so-called tapered slot coupler connected with the loudspeaker. Tapered slot speakers are disclosed in U.S. Pat. Nos. 2,816,629; 2,896,736; and 3,540,544.
Such tapered slot speakers have been found to generate an improved sound distribution pattern with wider angle dispersion within a wider frequency range, except for the low frequencies e.g. in the range from 50 to 200 hertz, the so-called bass range.
Conventional speakers for large listening areas are highly directional and are bulky and deficient in reproducing a flat frequency spectrum due to unavoidable mechanical resonances and standing waves in the speaker structure.
The prior art shows various sound reproducing systems wherein various forms of loudspeakers are combined to form enhanced sound reproduction systems.
U.S. Pat. No. 5,199,075 discloses a listening area which is served by a set of left and right speakers and a center speaker augmented by respective combination speakers that also include rearwardly slanted left and right speakers for generating a reflected sound wave "surround sound" effect.
U.S. Pat. No. 4,882,753 shows a multichannel stereophonic speaker system wherein different audio signals are produced which are caused to converge on a listening site in an enclosure.
U.S. Pat. No. 4,230,905 shows a stereophonic system which includes a pair of right and left channel sub-bass speakers in addition to the usual right and left channel main speakers.
The known sound reproduction systems all are based on the effect of mixing and blending the sound waves generated by variously configured speaker systems. Such blending of sound signals of different wavelengths from different speakers of the conventional types has the undesirable effect of creating areas of standing waves at discrete frequencies that leads to uneven sound distribution within the listening area. This effect is especially pronounced in a large enclosed area holding a large audience of listeners.
In accordance with the conventional systems, there is provided an acoustic sound system which has the directional effect of conventional speakers and their inherent cone of sound which is created by a dispersion pattern which becomes narrower as the frequency increases, as shown in FIG. 3. In contrast, speakers with tapered slot couplers have a dispersion which is uniform in its characteristics of radiation. Very little variation in sound distribution occurs with changes of frequency, as shown in FIG. 4.
Using speakers with tapered slot couplers with uniform high frequency dispersion have the further advantage that the sound energy is cut off above a horizontal plane 25 through the coupler. This allows a controlled sound pattern to the portion of the area to be covered from the speaker to receive a greater volume of sound energy. For that reason, the greatest energy is transmitted to the farthest point, and as one gets closer to the speaker, less and less energy is emitted for that area. Thus, in essence, uniform volume levels covering the entire listening area is attained. Both the length and the width of the area is blanketed by uniform levels, as shown in FIG. 5.
Because large area coverage such as theaters, arenas, outdoor amphitheaters, stadiums, etc. are difficult to cover with adequate uniformity, the rear surround channels usually have many speakers in order to attain the required effect.
The distribution patterns created by conventional front radiator systems make some areas louder than others and leave some areas with very little sound, if any. They also cause great reflections and reverberations as the sound is bounced off of interior surfaces detracting from the desired effect. In addition, sound that should appear to issue from the rear is perceived to come from the sides, and instead of hearing one sound source, the listener hears many. Since there are several sound sources, the sound waves intertwine creating a muddy effect from both the original sound and subsequent reflections and echoes.
In contrast, the acoustic reality surround sound speaker system according to the invention, allows the entire audience to hear the desired surround sound effect. Wherever one sits, one will hear each channel at the desired level. All of the acoustic effects desired by the recording engineer are apparent and enhanced in the system, according to the invention.
It is accordingly an object of the instant invention to provide a sound reproducing system that includes multiple speakers of the type having a tapered slot coupler, in the following called a tapered slot coupler-speaker. This term is to be understood to mean a speaker with a tapered slot coupler. These speakers provide a high degree of sound fidelity within a listening area or domain of any size.